The present invention relates to a silver halide photographic emulsion and a silver halide photographic material. More specifically, the present invention relates to a silver halide photographic emulsion which is high speed and hardly causes residual color after processing even in rapid processing, and to a silver halide photographic material.
A great deal of endeavors have been done to improve sensitivity of a silver halide photographic material and to reduce residual color after processing. The improvements of the sensitivity and the quality of photographic materials have been required more and more on one hand, the demands for shortening of photographic processing speed and the reduction of waste solutions in view of environmental protection have increased on the other hand in particular in recent years, hence the importance of techniques of spectrally sensitizing silver halide grains in high sensitivity without causing harmful influences such as fog and residual color has been increasingly raised.
It is known that the sensitizing dye for use in spectral sensitization gives large influences on the performances of silver halide photographic materials. In the sensitizing dye, a little structural difference largely affects photographic performances such as sensitivity, fog, storage stability and residual color after processing and photographic performances are also largely influenced by using two or more sensitizing dyes in combination, but it is difficult to forecast the effect in advance. Therefore, many researchers have synthesized a large number of sensitizing dyes and endeavored to examine the combined use of a variety of sensitizing dyes and investigate the photographic performances. However, it is the present situation that the photographic performances cannot be forecast yet.
The tabular grain is preferred for use in spectral sensitization in that it is large in the ratio of the surface area to the volume (specific surface area), hence it can absorb a large amount of sensitizing dye, but residual color after processing increases the more. Residual color is observed as fog and the problem of fog is more serious than in regular grains. On the other hand, the main current of the color developing time in color print materials is 180 seconds at present. Further shortening of the processing time is required but if the processing time is shortened, the residual amount of the sensitizing dye used in an emulsion increases and the problem of fog becomes more serious. Therefore, a technique which can reduce the fog attributable to residual color has been desired.
The objects of the present invention is to provide a silver halide photographic emulsion which is high speed and hardly causes residual color after processing even in rapid processing, and to provide a silver halide photographic material.
As a result of eager investigation of the problems, the present invention has been accomplished by the following means (1) to (12).
(1) A silver halide photographic emulsion which contains at least two sensitizing dyes represented by the following formula (I).
Dye-((A)rQ)q(M)mxe2x80x83xe2x80x83(I)
wherein Dye represents a dye moiety; A represents a linking group; Q represents a dissociable group; r represents 0 or 1; q represents an integer of 2 or more, provided that at least one Q represents xe2x80x94SO3H and at least one Q represents a dissociable group other than xe2x80x94SO3H; M represents a counter ion; and m represents a number of 0 or more necessary to neutralize the electric charge in the molecule, and when m represents 2 or more, M""s need not be the same.
(2) The silver halide photographic emulsion as described in the above item (1), wherein the dissociable group other than xe2x80x94SO3H is selected from the group consisting
of xe2x80x94COOH, xe2x80x94CONHSO2R, xe2x80x94SO2NHCOR, xe2x80x94SO2NHSO2R, xe2x80x94CONHCOR, xe2x80x94OSO3H, xe2x80x94PO(OH)2, xe2x80x94OPO(OH)2, xe2x80x94B(OH)2, xe2x80x94OB(OH)2, xe2x80x94ArOH, and xe2x80x94ArSH, wherein R represents an alkyl group, an aryl group, a heterocyclic group, an alkoxyl group, an aryloxy group, a heterocyclic oxy group, or an amino group, and Ar represents an arylene group.
(3) The silver halide photographic emulsion as described in the above item (1) or (2), wherein the sensitizing dyes are cyanine dyes.
(4) The silver halide photographic emulsion as described in the above item (1), (2) or (3), wherein the sensitizing dyes are represented by the following formula (II): 
wherein R1 and R2 each represents a substituted alkyl, aryl or heterocyclic group, and R1 is substituted with xe2x80x94SO3H and R2 is substituted with a dissociable group other than xe2x80x94SO3H; Y1 and Y2 each represents an atomic group necessary to form a 5- or 6-membered nitrogen-containing heterocyclic ring, and Y1 and Y2 may be condensed with other carbocyclic ring or heterocyclic ring; V1 and V2 each represents a substituent; n1 and n2 each represents an integer of 0 or more (preferably 6 or less, more preferably 2 or less), and when n1 and n2 each represents 2 or more, V1 and V2 may be the same with or different from each other; L1, L2, L3, L4, L5, L6 and L7 each represents a methine group; p1 represents 0, 1, 2 or 3, p2 and p3 each represents 0 or 1, and when p1 represents 2 or 3, repeating L2 and L3 may be the same with or different from each other; M1 represents a counter ion; and m1 represents a number of 0 or more necessary to neutralize the electric charge in the molecule.
(5) The silver halide photographic emulsion as described in the above item (1), (2), (3) or (4), wherein at least one sensitizing dye is represented by the following formula (III) and at least one sensitizing dye is represented by formula (IV): 
wherein R11 and R12 each represents a substituted alkyl, aryl or heterocyclic group, and R11 is substituted with xe2x80x94SO3H and R12 is substituted with a dissociable group other than xe2x80x94SO3H; X11 and X12 each represents an oxygen atom, a sulfur atom, a selenium atom, NR15, CR16R17, or L13xe2x95x90L14; R15, R16 and R17 each represents a substituted or unsubstituted alkyl, aryl or heterocyclic group; L13 and L14 each represents a methine group; V11 and V12 each represents a substituent; n11 and n12 each represents an integer of 0 or more (preferably 4 or less, more preferably 2 or less), and when n11 and n12 each represents 2 or more, V11 and V12 may be the same with or different from each other; L11 represents a methine group;M11 represents a counter ion; and m11 represents a number of 0 or more necessary to neutralize the electric charge in the molecule; 
wherein R13 and R14 each represents a substituted alkyl, aryl or heterocyclic group, and at least one of R13 and R14 is substituted with xe2x80x94SO3H and the other is substituted with a dissociable group other than xe2x80x94SO3H; X13 and X14 each represents an oxygen atom, a sulfur atom, a selenium atom, NR18 , CR19R20, or L15xe2x95x90L16; R18, R19 and R20 each represents a substituted or unsubstituted alkyl, aryl or heterocyclic group; L15 and L16 each represents a methine group; Z11 represents a benzene ring or a naphthalene ring; Z12 represents a naphthalene ring; V13 and V14 each represents a substituent; n13 and n14 each represents an integer of 0 or more (n13 represents preferably 4 or less, more preferably 2 or less, and n14 epresents preferably 6 or less, more preferably 2 or less), and when n13 and n14 each represents 2 or more, V13 and V14 may be the same with or different from each other; L12 represents a methine group; M12 represents a counter ion; and m12 represents a number of 0 or more necessary to neutralize the electric charge in the molecule.
(6) The silver halide photographic emulsion as described in the above item (5), wherein the dissociable group other than xe2x80x94SO3H is selected from the group consisting
of xe2x80x94COOH, xe2x80x94CONHSO2R, xe2x80x94SO2NHCOR, xe2x80x94SO2NHSO2R, and xe2x80x94CONHCOR, wherein R represents an alkyl group, an aryl group, a heterocyclic group, an alkoxyl group, an aryloxy group, a heterocyclic oxy group, or an amino group.
(7) The silver halide photographic emulsion as described in the above item (1), (2), (3) or (4), wherein at least one sensitizing dye is represented by the following formula (V) and at least one sensitizing dye is represented by formula (VI): 
wherein R21 and R22 each represents a substituted alkyl, aryl or heterocyclic group, and at least one of R21 and R22 is substituted with xe2x80x94SO3H and the other is substituted with a dissociable group other than xe2x80x94SO3H; X21 and X22 each represents an oxygen atom, a sulfur atom, a selenium atom, NR25, CR26R27, or L27xe2x95x90L28; R25, R26 and R27 each represents a substituted or unsubstituted alkyl, aryl or heterocyclic group; L27 and L28 each represents a methine group; V21 and V22 each represents a substituent; n21 and n22 each represents an integer of 0 or more (preferably 4 or less, more preferably 2 or less), and when n21 and n22 each represents 2 or more, V21 and V22 may be the same with or different from each other; L21, L22 and L23 each represents a methine group; M21 represents a counter ion; and m21 represents a number of 0 or more necessary to neutralize the electric charge in the molecule; 
wherein R23 and R24 each represents a substituted alkyl, aryl or heterocyclic group, and at least one of R23 and R24 is substituted with xe2x80x94SO3H and the other is substituted with a dissociable group other than xe2x80x94SO3H; X23 and X24 each represents an oxygen atom, a sulfur atom, a selenium atom, NR28, CR29R30, or L29xe2x95x90L30; R28, R29 and R30 each represents a substituted or unsubstituted alkyl, aryl or heterocyclic group; L29 and L30 each represents a methine group; Z21 represents a benzene ring or a naphthalene ring; Z22 represents a naphthalene ring; V23 and V24 each represents a substituent; n23 and n24 each represents an integer of 0 or more (when Z21 represents a benzene ring, n23 represents 4 or less, preferably 2 or less, and when Z21 represents a naphthalene ring, n23 represents 6 or less, preferably 2 or less, and n24 represents 6 or less, preferably 2 or less), and when n23 and n24 each represents 2 or more, V23 and V24 may be the same with or different from each other; L24, L25 and L26 each represents a methine group; M22 represents a counter ion; and m22 represents a number of 0 or more necessary to neutralize the electric charge in the molecule.
(8) The silver halide photographic emulsion as described in the above item (7), wherein the dissociable group other than xe2x80x94SO3H is selected from the group consisting
of xe2x80x94COOH, xe2x80x94CONHSO2R, xe2x80x94SO2NHCOR, xe2x80x94SO2NHSO2R, and xe2x80x94CONHCOR, wherein R represents an alkyl group, an aryl group, a heterocyclic group, an alkoxyl group, an aryloxy group, a heterocyclic oxy group, or an amino group.
(9) The silver halide photographic emulsion as described in any of the above items (1) to (8), wherein 50% or more of the entire projected area of the silver halide grains in the emulsion is accounted for by tabular grains having an aspect ratio of 2 or more.
(10) The silver halide photographic emulsion as described in any of the above items (1) to (8), wherein the emulsion is chemically sensitized with a selenium sensitizer.
(11) A silver halide photographic material which comprises a support having provided thereon at least one emulsion layer containing the silver halide photographic emulsion described in any of the above items (1) to (10).